Bac Calculator
Estimate your Blood Alcohol Content (BAC) based on drinks consumed, body weight, and time elapsed.
Published by:
isCalculator Editorial Team
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How to use this tool?
How to Use the BAC Calculator
This tool estimates your Blood Alcohol Concentration (BAC) based on standard drink intake. Follow these steps:
- Select Gender – Choose Male or Female (affects the calculation constant).
- Enter Weight – Input your weight in pounds (lbs) (range: 50–500).
- Enter Number of Drinks – Use whole or half drinks (e.g., 3 or 2.5). Range: 0–100.
- Enter Hours Since First Drink – Time elapsed in hours (e.g., 2 or 1.5). Range: 0–24.
- Click "Calculate BAC" – Your result will appear below with a color-coded interpretation:
- Green: Likely not impaired (BAC < 0.02%)
- Yellow: May be impaired (BAC 0.02–0.08%)
- Red: Legally intoxicated (BAC ≥ 0.08%)
Note: All inputs are required. Invalid entries (e.g., out-of-range values) will show error highlights. The formula used is displayed below the result.
Previous Results
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Frequently Asked Questions
BAC is estimated using the Widmark formula: BAC = (Drinks × 0.6 × 100 × 1.055) / (Weight × r) - 0.015 × Hours, where r is 0.73 for males and 0.66 for females.
In most US states, a BAC of 0.08% is the legal limit for driving. At this level, impairment is significant.
This calculator provides an estimate. Actual BAC depends on many factors including metabolism, food consumption, and individual differences.
